We’ve got the Senate. People who serve there are called Senators.
We’ve got Congress. Why is it THE Senate, and just Congress? Not THE Congress?
Also, why aren’t the folks there called Congressors? Instead of Congressman and Congresswoman? Or (worse idea), why not call Senators Senatmen and Senatwomen?
Obviously the first approach is a better one… so why are we stuck with two parts of the same house with such different rules?